Optical information reproducing apparatus and method thereof

Abstract

An optical information reproducing apparatus includes a light-receiving unit that receives a first reproduction light of an information output from a first region of an information recording layer and a second reproduction light of an information output from a second region of the information recording layer, the first region and the second region being formed by dividing the information recording layer with a line segment that intersects a plane of incidence of the reference light and a plane of the information recording layer, and outputs a first reproduction signal that is a reproduction signal of the first region and a second reproduction signal that is a reproduction signal of the second region.

1 . An optical information reproducing apparatus comprising:
 a light-receiving unit that receives a first reproduction light of an information output from a first region of an information recording layer and a second reproduction light of an information output from a second region of the information recording layer, the first region and the second region being formed by dividing the information recording layer with a line segment that intersects a plane of incidence of the reference light and a plane of the information recording layer, and outputs a first reproduction signal that is a reproduction signal of the first region and a second reproduction signal that is a reproduction signal of the second region;   a driving unit that rotates the optical information recording medium in a thickness direction of the optical information recording medium and in a surface direction of the optical information recording medium;   a differentiator that generates a servo signal by performing a differential operation on the first reproduction signal and on the second reproduction signal; and   a record controlling unit that controls the light source to emit the illumination light, and performs angular multiplex recording of the information on the information recording layer, controlling rotation by the driving unit, adjusting a rotation angle in the thickness direction based on the servo signal.   
   
   
       2 . The apparatus according to  claim 1 , further comprising:
 a dividing unit that divides the first reproduction light and the second reproduction light into an information reproduction light and a servo reproduction light for generating a servo signal; wherein   the light-receiving unit includes an information-reproduction-light receiving unit and a servo-light receiving unit, and   the differentiator generates a servo signal by performing the differential operation on the first reproduction signal and the second reproduction signal.   
   
   
       3 . The apparatus according to  claim 2 , further comprising a diffraction element that diffracts a first servo reproduction light from the first region and a second servo reproduction light from the second region, and collects the first servo reproduction light and the second servo reproduction light onto the servo-light receiving unit. 
   
   
       4 . The apparatus according to  claim 2 , wherein the servo-light receiving unit is a photodetector. 
   
   
       5 . The apparatus according to  claim 1 , further comprises
 a diffraction element that diffracts only the first servo reproduction light and the second servo reproduction light and collects the first servo reproduction light and the second servo reproduction light on the servo-light receiving unit.   
   
   
       6 . An optical information reproducing method comprising:
 receiving a first reproduction light of an information output from a first region of an information recording layer and a first reproduction light of an information output from a second region of the information recording layer, the first region and the second region being formed by dividing the information recording layer with a line segment that intersects a plane of incidence of the reference light and a plane of the information recording layer, and outputting a first reproduction signal that is a reproduction signal of the first region and a second reproduction signal that is a reproduction signal of the second region;   rotating the optical information recording medium by a driving unit in a thickness direction of the optical information recording medium and in a surface direction of the optical information recording medium;   generating a servo signal by performing a differential operation on the first reproduction signal and on the second reproduction signal; and   controlling the light source to emit the illumination light, and performing angular multiplex recording of the information on the information recording layer, controlling rotation by the driving unit, adjusting a rotation angle in the thickness direction based on the servo signal.